No deposit bonus codes for existing customers are promotional offers that allow players to enjoy additional rewards without having to make a new deposit. These codes can provide free spins, bonus cash, or other incentives, enhancing the gaming experience and encouraging loyalty. Typically, players can redeem these codes through their accounts, making it easy to access extra funds or spins. However, it's essential to read the terms and conditions, as wagering requirements and expiration dates may apply. Overall, these bonuses are a great way for casinos to reward their loyal players.